One of the most common types of assays used as a rapid point of care test to detect a particular analyte in a biological sample is a lateral flow strip-based assay. Such assays typically contain a binding partner for the analyte of interest coupled to a detectable label (i.e. labeled conjugates) and a porous membrane on which a capture protein (e.g. antibody or antigen) capable of binding the analyte of interest is immobilized. Labeled conjugates that are commonly used in these types of assays are antibodies or antigens coupled to gold nanoparticles or colored latex particles. An analyte present in the sample will bind to the labeled conjugate to form a complex. The complex continues to migrate through the porous membrane to the region where the capture protein is immobilized at which point the complex of analyte and labeled conjugate will bind to the capture protein. The presence of the analyte is then determined by detecting the labeled conjugate in the capture region of the porous membrane (e.g. by a color change of the capture line).
Although lateral flow strip-based assays have proven useful for rapid detection of some analytes in the clinical setting, such assays suffer from several disadvantages. For example, lateral flow strip-based assays require a series of overlapping porous materials to achieve efficient sample flow through the device. Construction of such devices can be cumbersome and somewhat costly depending on the porous materials that are employed. Also, lateral-strip based assays are inherently limited by their sensitivity due to the occurrence of a single binding event and are often limited to a qualitative analysis. In addition, detection of multiple analytes in a single sample simultaneously is often difficult to achieve with conventional lateral flow strip-based assays.
Thus, there is a need in the art to develop novel devices and methods for the detection of multiple analytes in a sample, particularly a biological sample, that can provide quantitative results as well as qualitative results.